In U.S. Pat. No. 3,819,893, issued June 25, 1974, to Jawelak et al, there is set forth an oil-type circuit-breaker having a laterally-disposed oil-pumping cylinder with improved auxiliary shunting contacts for increased current-carrying ability. The function of the oil pump in the aforesaid Jawelak patent is to improve the circuit-breaker performance during low-current interruption, when inadequate pressures may develop, or be generated within the oil-grid structure during such low-current interruption, and an auxiliary, supplementary flow of oil under pressure is desirable to engage the arc, which is established to effect its extinction. In addition, the foresaid patent teaches the concept, broadly, of a shunting contact structure to provide two electrically-parallel separate pairs of separable contacts acting collectively to increase the current rating capability of the circuit-breaker in the closed-circuit position. This enables high current ratings to be applicable, or assigned to the circuit-breaker.